EP0182096A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Method and apparatus for improved control and time sharing of an echo canceller
Assignee: International Business Machines Corp
•
Filing: 1985-10-15
•
Granted: —
•
Expires: 2005-10-15
Abstract
Abstract An improved echo canceller control method utilizes two adaptive level detectors for controlling or inhibiting the updating of coefficients in the echo canceller. Updating is permitted only when an actual received signal is present and no transmit signal as measured by the adaptive level detector exists. During periods when no transmit or receive signals are present, update is inhibited and the adaptive level detector establishes a noise reference level. When transmission activity is present but no receive activity is present, inhibiting of the echo canceller updating allows the adaptive level detector to seek and establish the background noise reference level. When actual double talk, i.e., both receive and transmit activities are present occurs, updating is also inhibited for the same reason. If the coefficients are separately stored in association with each channel as is the case in this invention, the echo canceller coefficients are loaded whenever updating is to take place for a given channel.
Inventors
- 👤 Gardner Dulany Jones, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 11:54
CPC Classifications
H; H04; H04B; H04B3/00; H04B3/02; H04B3/20; H04B3/23; H04B3/234
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
80 words
An improved method of controlling coefficient calculation in an echo canceller comprising steps of: detecting received signal activity in a first adaptive level detector; and detecting the combined noise and signal output level of transmission activity in a second adaptive level detector; and recomputing the coefficients in an echo canceller when the output of said first adaptive level detector indicates that a signal is present and the output of said second level detector indicates that no transmission activity is present.
Claim 2
Dependent Claim
80 words
An improved method of controlling coefficient calculation in an echo canceller comprising steps of: detecting received signal activity in a first adaptive level detector; and detecting the combined noise and signal output level of transmission activity in a second adaptive level detector; and recomputing the coefficients in an echo canceller when the output of said first adaptive level detector indicates that a signal is present and the output of said second level detector indicates that no transmission activity is present.
Claim 3
Dependent Claim
35 words
A method as described in Claim 1 and further comprising a step of inhibiting computation of said coefficients for said echo canceller whenever transmission activity as sensed by said second adaptive level detector is present.
Claim 4
Dependent Claim
29 words
A method as described in Claim 2 and further comprising a step of inhibiting computation of said coefficients whenever both said adaptive level detectors indicate absence of signal activity.
Claim 5
Dependent Claim
47 words
A method as described in Claim 1 and further comprising a step of supplying the output from said first adaptive level detector to an input of said second adaptive level detector to serve as a threshold of noise activity for setting the adaptive level in said detector.
Claim 6
Dependent Claim
85 words
A method as described in Claim 4 and further comprising a step of comparing in said second adaptive level detector the output signal energy level including any transmitted signal plus echo energy to said noise threshold; said noise threshold being established by said level detector receiving said first adaptive level detector output of signal activity present, said second adaptive level detector providing an output indicating transmission signal activity only when said transmitted signal and echo energy level exceeds said established threshold in said level detector.
Claim 7
Dependent Claim
88 words
A method as described in Claim 1 or 2 or 3 or 4 or 5 and further comprising steps of: storing said coefficients in a memory as the coefficients to be used for a given port in a multiport communication system; and recomputing said coefficients for other ports and storing their respective recomputed coefficients whenever said recomputing for a said given port is halted due to the presence of transmission activity on said given port or due to the absence of received signal activity at said given port.
Claim 8
Dependent Claim
47 words
A method as described in Claim 1 or 2 or 3 or 4 or 5 and further comprising steps of: sharing said recomputing in a multiport application by multiplexing the recomputing to other active ports during times when a given port is either inactive or is transmitting.
Claim 9
Dependent Claim
96 words
Improved apparatus for controlling coefficient recalculation in an echo canceller, comprising: a first adaptive level detector means for detecting received signal activity on a communication port; and second adaptive level detector means for detecting the combined noise and signal output level of transmission activity at said communications port; and means for recomputing the coefficients in an echo canceller when the output of said first adaptive level detector means indicates that a signal input is being received and the output of said second adaptive level detector means indicates that no transmission activity is present at said port.
Claim 10
Dependent Claim
96 words
Improved apparatus for controlling coefficient recalculation in an echo canceller, comprising: a first adaptive level detector means for detecting received signal activity on a communication port; and second adaptive level detector means for detecting the combined noise and signal output level of transmission activity at said communications port; and means for recomputing the coefficients in an echo canceller when the output of said first adaptive level detector means indicates that a signal input is being received and the output of said second adaptive level detector means indicates that no transmission activity is present at said port.
Claim 11
Dependent Claim
32 words
Apparatus as described in Claim 8, and further comprising: means for inhibiting computation of said coefficients for said echo canceller whenever transmission activity is sensed by said second adaptive level detector means.
Claim 12
Dependent Claim
33 words
Apparatus as described in Claim 9 and further comprising: further means for inhibiting computation of said coefficients whenever both said first and second adaptive level detector means indicate the absence of signal input.
Claim 13
Dependent Claim
44 words
Apparatus as described in Claim 8 and further comprising: means for supplying the output from said first adaptive level detector means to an input of said second adaptive level detector means for setting the adaptive threshold level in said second adaptive level detector means.
Claim 14
Dependent Claim
87 words
Apparatus as described in Claim 8 or 9 or 10 or 11 and further comprising: memory means for storing said computed coefficients in association with given specific ports in a multiport communications system; and means for recomputing coefficients for other said ports in said system and storing their respective recomputed coefficients in said memory means whenever said recomputing for any given port is halted due to the presence of transmission activity at said port or due to the absence of received signal activity at said given port.
Claim 15
Dependent Claim
31 words
Apparatus as described in Claim 8 or 9 or 10 or 11 and further comprising: means for multiplexing said computing means over a population of ports in a multiport communications system.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.